It is simply a fact that tension slows you down, reduces your power, and restricts your freedom. This is one of the reasons that serious folks from other martial arts think Aikido is bullshit. They look at this grab the wrist stuff and see what a joke it is.

I have never met a serious - as in high ranking - martial artist who didn't respect aikido.

we can make our minds so like still water, and so live for a moment with a clearer, perhaps even with a fiercer life
w b yeats